email validation for form in JS

<form action="cakes.php" method="post">

  <tr>

    <td>Email-Id *</td>

    <td><input id="email" name="mail" required/></td>

  </tr>

</form>

<script type="text/javascript">

$("#email").change(function(){
var x=$(this).val();
var atpos=x.indexOf("@");
var dotpos=x.lastIndexOf(".");
if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length)
  {
  alert("Not a valid e-mail address");
  return false;
  }
});
</script>